Papers by Jordan A. Goodman
Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)
The Cygnus Cocoon region is a complex region containing an OB star cluster that is prominent in t... more The Cygnus Cocoon region is a complex region containing an OB star cluster that is prominent in the TeV energy range. Located in this region is 3HWC J2031+415, a significant TeV gamma-ray source whose emission is possibly associated with 2 components, the Cygnus OB2 star cluster and a pulsar wind nebula (PWN). In this work, several modelling methods are presented to best describe the emission. These models disentangle emission believed to be from the Cocoon and isolate the component emitted by the probable PWN. I will present several spectral models to describe the emission of the probable PWN using the latest data set from the High-Altitude Water Cherenkov (HAWC) observatory. Furthermore, I will present an energy morphology study of the PWN component of 3HWC J2031+415 in distinct energy bands.
Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)
Nowadays the implementation of artificial neural networks in high-energy physics has obtained exc... more Nowadays the implementation of artificial neural networks in high-energy physics has obtained excellent results on improving signal detection. In this work we propose to use neural networks (NNs) for event discrimination in HAWC. This observatory is a water Cherenkov gamma-ray detector that in recent years has implemented algorithms to identify horizontal muon tracks. However, these algorithms are not very efficient. In this work we describe the implementation of three NNs: two based on image classification and one based on object detection. Using these algorithms we obtain an increase in the number of identified tracks. The results of this study could be used in the future to improve the performance of the Earth-skimming technique for the indirect measurement of neutrinos with HAWC.
Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)
A major task in ground-based gamma-ray astrophysics analyses is to separate events caused by gamm... more A major task in ground-based gamma-ray astrophysics analyses is to separate events caused by gamma rays from the overwhelming hadronic cosmic-ray background. In this talk we are interested in improving the gamma ray regime below 1 TeV, where the gamma and cosmic-ray separation becomes more difficult. Traditionally, the separation has been done in particle sampling arrays by selections on summary variables which distinguish features between the gamma and cosmic-ray air showers, though the distributions become more similar with lower energies. The structure of the HAWC observatory, however, makes it natural to interpret the charge deposition collected by the detectors as pixels in an image, which makes it an ideal case for the use of modern deep learning techniques, allowing for good performance classifers produced directly from low-level detector information.
Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)
Galaxy clusters' dynamics constitute a major piece of evidence for the existence of dark matter i... more Galaxy clusters' dynamics constitute a major piece of evidence for the existence of dark matter in astrophysical structures. The decay or annihilation of dark matter particles is hypothesized to produce a steady flux of very-high-energy gamma rays correlated with the direction of a cluster of galaxies. The Virgo cluster, being only 16 Mpc away and spanning several degrees across the sky is an excellent target to search for signatures of particle dark matter interactions. The High Altitude Water Cherenkov (HAWC) observatory, due to its wide field of view and sensitivity to gamma rays at an energy-scale of 300 GeV-100 TeV is well-suited to perform the aforementioned search. We perform a search from the Virgo cluster for gamma-ray emission, assuming various dark matter sub-structure models using 1523 days of HAWC data. Our results provide the strongest constraints on the decay lifetime of dark matter for masses above 20 TeV.
Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)
Characterizing-ray sources with HAL (HAWC Accelerated Likelihood) and 3ML Chad Brisbois , * on be... more Characterizing-ray sources with HAL (HAWC Accelerated Likelihood) and 3ML Chad Brisbois , * on behalf of the HAWC Collaboration
Proceedings of 36th International Cosmic Ray Conference — PoS(ICRC2019), 2019
Fermi-LAT Collaboration, the HAWC Collaboration † , the H.E.S.S. Collaboration, the MAGIC Collabo... more Fermi-LAT Collaboration, the HAWC Collaboration † , the H.E.S.S. Collaboration, the MAGIC Collaboration ‡ and the Veritas Collaboration. § * Speaker. † http:www.hawc-observatory.orgcollaborationicrc2019.php ‡ https://magic.mpp.mpg.de/ § for all collaboration lists see PoS(ICRC2019)1177
AIP Conference Proceedings, 1994
This paper describes how data from a new type of air shower detector, MILAGRO, can shed light on ... more This paper describes how data from a new type of air shower detector, MILAGRO, can shed light on a variety of interesting problems in astrophysics. MILAGRO has the capability to make observations of VHE/UHE emission from the recently discovered TeV gamma-ray source Markarian 421, an Active Galactic Nucleus (AGN). An observation of the attenuation of this signal in the range of 1 - 20 TeV can be used to make the first measurement of the intergalactic infrared radiation. The authors also describe how MILAGRO can improve the existing limits on the density of Primordial Black Holes (PBH) by three orders of magnitude. In addition, MILAGRO will have a large aperture and continuous operation which gives it the capability to search for VHE gamma-ray bursts.
Physical Review D, 1984
A critical analysis of experimental data on high-energy muons in air showers is carried out to de... more A critical analysis of experimental data on high-energy muons in air showers is carried out to derive information about the composition of primary cosmic rays near the bend in the energy spectrum at-10' eV. A set of Monte Carlo simulated air showers from different elemental species have been used to study expectations for three different experiments: the Tien Shan study of muons with energy above 5 GeV at an altitude of 690 g/crn, the Moscow State University experiment for muons with energy above 10 GeV at sea level, and the Kolar-gold-field experiment for muons with energy above 220 CxeV at 930 g/cm. The results show that when showers are grouped according to shower size the sensitivity of the total number of high-energy muons to primary composition is greatly reduced. In fact, it is found that the data cannot discriminate between models which assume energy-independent low-energy composition and those which assume energy spectra which steepen above some value of rigidity cutoff around 10' eV/nucleon. In order to make a compositionsensitive measurement of the high-energy muon component it is necessary to make these measurements at fixed energy rather than at fixed shower size.
The Astrophysical Journal, 1995
The majority of the cosmic rays in our Galaxy with energies in the range of 110 10-10 14 eV are t... more The majority of the cosmic rays in our Galaxy with energies in the range of 110 10-10 14 eV are thought to be accelerated in supernova remnants (SNRs). Measurements of SNR gamma-ray spectra in this energy region could support or contradict this concept. The Energetic Gamma-Ray Experiment Telescope (EGRET) collaboration has reported six sources of gamma rays above 10 8 eV whose coordinates are coincident with SNRs. Five of these sources are within the field of view of the CYGNUS extensive air shower detector. A search of the CYGNUS data set reveals no evidence of gamma-ray emission at energies 110 14 eV for these five SNRs. The flux upper limits from the CYGNUS data are compared to the lower energy fluxes measured with the EGRET detector using Drury, Aharonian, & Völk's recent model of gamma-ray production in the shocks of SNRs. The results suggest one or more of the following: (1) the gamma-ray spectra for these five SNRs soften by about 10 14 eV, (2) the integral gamma-ray spectra of the SNRs are steeper than about E Ϫ1.3 , or (3) most of the gamma rays detected with the EGRET instrument for each SNR are not produced in the SNR's shock but are produced at some other site (such as a pulsar).
Physical Review D, 1985
We present the results of an experimental' search for energetic particles whicharrive at sea leve... more We present the results of an experimental' search for energetic particles whicharrive at sea level delayed with respect to the shower front, with an order of magnitude greater exposure than previous experiments. The experiment was sensitive to showers from cosmic rays between I05 and lO7 GeV per nucleus. No evidence for the existence of heavy long lived particles in air showers was found. We set an upper limit to the flux of these particles at the 90% confidence level of 1.4 x lO-12 cm-2sr-ls-l.
Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021), 2021
A GeV to TeV view of shell-type SNRs Henrike Fleischhack * on behalf of the Fermi Large Area Tele... more A GeV to TeV view of shell-type SNRs Henrike Fleischhack * on behalf of the Fermi Large Area Telescope Collaboration and on behalf of the HAWC Collaboration
Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)
The TeV gamma-ray source MGRO J1908+06 is one of the highest-energy sources known, with observed ... more The TeV gamma-ray source MGRO J1908+06 is one of the highest-energy sources known, with observed emission by the High Altitude Water Cherenkov (HAWC) Observatory extending well past 100 TeV. The source exhibits both energy-dependent morphology and a spatially-dependent spectral index. The emission is likely to be dominantly leptonic, and associated with the radioquiet PSR J1907+0602. However, one-population models do not describe the data well; a second particle population is needed to explain the shape of the spectral energy distribution at the highest energies. This component can be well-described by either leptonic or hadronic hypotheses. We discuss this feature and implications for detection by multi-wavelength and multi-messenger experiments.
Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021), 2021
The Cygnus Cocoon is the first gamma-ray superbubble powered by a massive stellar association, th... more The Cygnus Cocoon is the first gamma-ray superbubble powered by a massive stellar association, the OB2 association. It was postulated that the combined effects of the stellar winds of all the massive O-type stars of the OB2 association can accelerate the cosmic rays to PeV energy in the Cocoon. The conclusive proof of acceleration to PeV energy in the Cocoon will identify the stellar association as a PeV cosmic-ray accelerator, known as PeVatron. However, the Cocoon has been previously studied only up to 10 TeV. In this contribution, using 1343 days of High Altitude Water Cherenkov (HAWC) observatory data, we present the morphological and spectral study of the Cocoon above 1 TeV to beyond 100 TeV. The analysis at higher TeV energies reveals a softer spectrum compared to the GeV gamma-ray observation. This result suggests that the accelerator's efficiency decreases around hundreds of TeV, or after being accelerated, the highest-energy protons escape the region. The study above 10 TeV presented here demonstrates how CR accelerators operate in these extreme energies and how particle transport impacts high-energy emission.
Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)
A wide range of data formats and proprietary software have traditionally been used in γ-ray astro... more A wide range of data formats and proprietary software have traditionally been used in γ-ray astronomy, usually developed for a single specific mission or experiment. However, in recent years there has been an increasing effort towards making astronomical data open and easily accessible. Within the γ-ray community this has translated to the creation of a common data format across different γ-ray observatories: the "gamma-astro-data-format" (GADF). Based on a similar premise, opensource analysis packages, such as Gammapy, are being developed and aim to provide a single, robust tool which suits the needs of many experiments at once. In this contribution we show that data from the High-Altitude Water Cherenkov (HAWC) observatory can be made compatible with the GADF and present the first GADF-based production of event lists and instrument response functions for a ground-based wide-field instrument. We use these data products to reproduce with excellent agreement the published HAWC Crab spectrum using Gammapy. Having a common data format and analysis tools facilitates joint analysis between different experiments and effective data sharing. This will be especially important for next-generation instruments, such as the proposed Southern Wide-field Gamma-ray Observatory (SWGO) and the planned Cherenkov Telescope Array (CTA).
Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)
Two cosmic-ray experiments, PAMELA and AMS-02, measured an abnormal positron excess above 10 GeV.... more Two cosmic-ray experiments, PAMELA and AMS-02, measured an abnormal positron excess above 10 GeV. This excess is well understood, but it has been considered direct evidence of dark matter. However, this excess could be produced by nearby pulsars too. The HAWC collaboration previously studied the extended gamma-ray emission of two nearby pulsars, Geminga and PSR B0656+14, but found no significant contribution to this excess from these pulsars. The previous study of HAWC led to the reinterpretation of our result and initiated the concept of inverse Compton (IC) halos. Fitting a new halo model and 1343 days of data from the HAWC gamma-ray observatory may better constrain the contribution of these pulsars to the positron excess. This halo model utilizes 3D templates of gamma-ray emission from electron IC interactions to fit the diffusion coefficient and electron injection spectral index. This model can further help to study the energy-dependent diffusion and incorporate anisotropic diffusion with the proper motion of the pulsar.
Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)
Background showers triggered by hadrons represent over 99.9% of all particles arriving at groundb... more Background showers triggered by hadrons represent over 99.9% of all particles arriving at groundbased gamma-ray observatories. An important stage in the data analysis of these observatories, therefore, is the removal of hadron-triggered showers. Currently, the High-Altitude Water Cherenkov (HAWC) gamma-ray observatory employs an algorithm based on a single cut in two variables, unlike other ground-based gamma-ray observatories (e.g. H.E.S.S., VERITAS), which employ a large number of variables to separate the primary particles. In this work, we explore machine learning techniques (Boosted Decision Trees and Neural Networks) to identify the primary particles detected by HAWC. Our new gamma/hadron separation techniques were tested on data from the Crab nebula, the standard reference in Very High Energy astronomy, showing an improvement compared to the standard HAWC background rejection method.
Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)
The High Altitude Water Cherenkov (HAWC) Observatory is a wide-field-of-view gamma-ray observator... more The High Altitude Water Cherenkov (HAWC) Observatory is a wide-field-of-view gamma-ray observatory that is optimized to detect gamma rays between 300 GeV and several hundred TeV. The HAWC Collaboration recently released their third source catalog (3HWC), which contains 65 sources. One of these sources, the ultra-high-energy gamma-ray source 3HWC J1908+063, may exhibit a hardening of the spectral index at the highest energies (above 56 TeV). At least two populations of particles are needed to satisfactorily explain the highest energy emission. This second component could be leptonic or hadronic in origin. If it is hadronic in origin, it would imply the presence of protons with energies up to ∼1 PeV near the source. We have searched other 3HWC sources for the presence of this spectral hardening feature. If observed, this would imply that the sources could make good PeVatron candidates.
Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)
a on behalf of the HAWC Collaboration
Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)
Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021), 2021
The volcanoes surrounding the HAWC observatory provide varying material depths from open sky to o... more The volcanoes surrounding the HAWC observatory provide varying material depths from open sky to over 15 km of rock for nearly horizontal muon trajectories. The muon integral intensity as a function of material depth may be determined from the rate of muons as a function of arrival direction near the horizon. A Hough transform algorithm is used to identify nearly-horizontal muons traversing the HAWC observatory by finding a line in the 3d point cloud of PMT hits (xi,yi, and cti). The arrival direction of the muon can be estimated from this line. Background Extensive Air Shower (EAS) fragments are identified by the presence of a lateral extension of PMT hits in a plane normal to the muon candidate trajectory. A geometry-based simulation has been developed to improve and estimate arrival direction reconstruction resolution and effective area. A description of the reconstruction techniques and estimates of detector resolution, backgrounds, and effective area as a function of arrival dir...
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Papers by Jordan A. Goodman